Capacitive liquid crystal touch panels that are recently used in various applications detect a change in electrostatic capacitance caused by an object coming close to the panel surface and convert position information of the object coming close to the panel surface into an electric signal.
A conductive substrate used in a capacitive liquid crystal touch panel is arranged on the surface of the liquid crystal panel, and as such, the material of a conductive layer of the conductive substrate is required to have low reflectance and low visibility.
Thus, a material with low reflectance and low visibility is used as the material of the conductive layer of a conductive substrate used in a capacitive touch panel, and the conductive layer is formed on a transparent substrate or a transparent film. For example, Patent Document 1 discloses a transparent conductive film for a touch panel including an ITO (indium oxide-tin) film formed as a transparent conductive film on a polymer film.
In recent years, the screens of displays provided with touch panels are becoming increasingly larger, and as such, there is a demand for increasing the size of conductive substrates, such as transparent conductive films for touch panels. However, because ITO has high electrical resistance and is susceptible to signal degradation, it is not suitable for use in a large panel.
In this respect, use of a metal foil made of copper or the like instead of an ITO film has been contemplated as described in Patent Documents 2 and 3, for example. However, when a metal foil made of copper or the like is used in place of an ITO film, for example, because a metal foil made of copper or the like has metallic luster, visibility of the liquid display panel may be degraded due to light reflection.
Accordingly, a conductive substrate having a metal layer made of copper or the like and a blackened layer made of a material that can restrict light reflection at the surface of the metal foil made of copper or the like is being contemplated. By forming such a blackened layer, light reflectance of the conductive substrate can be reduced and wiring formed by patterning a metal layer may be less visible such that visibility of the liquid crystal panel may be improved, for example.